The present invention relates to ground treatment and particularly, but not exclusively, to the compaction of ground such as derelict industrial sites, in preparation for building.
The invention provides a ground treatment device, the device being weighted to provide ground treatment by dropping the device on the ground, and the device having a relatively narrow nose providing, in use, the point of first contact with the ground, and the device widening away from the nose.
Preferably the device is weighted to provide ground compaction. Preferably the nose is pointed. The nose may be the tip of a conical or frustoconical portion of the device. The device preferably has a shoulder which projects outwardly from the device. The shoulder may be an annular projection around substantially the whole periphery of the device. The device preferably widens from the nose to the shoulder. The shoulder is preferably spaced from the nose by a distance so chosen that, when the device is dropped from a predetermined height, the nose will embed in the ground without the shoulder reaching the ground if the ground is compacted to or above a predetermined degree. Preferably the shoulder will engage the ground if the ground is inadequately compacted, to resist the device becoming buried. The shoulder may be provided by a plate member. The plate member may be substantially square, preferably of side length of about 2 m.
Preferably the device widens away from the nose at an angle of substantially 45xc2x0 or greater. The nose may be a substantially conical tip and may have a cone angle of substantially 45xc2x0. The base diameter of the conical tip may be approximately 1 m.
The device may comprise a body of substantially frusto-conical form, which may be located above the tip during use, and may have a cone angle greater than 14xc2x0, preferably in the region of 14-20xc2x0, for example 17xc2x0. The frusto-conical body may have a base diameter of about 1.5 m and may have a minimum diameter of about 1 m.
The device preferably comprises attachment means by which the device may hang prior to dropping, the hanging means being so located on the device as to cause the nose to be substantially the lowest part of the device when so hung.
Preferably the device has a weight of at least 2,500 kg, preferably at least 4,000 kg, and may be 15,000 kg. The device may have a nose of cross-section less than about 0.5 m2.
In an alternative, the device may comprise a plurality of relatively narrow noses as aforesaid, which may be formed on respective projections from a common member. Each nose may be substantially conical or pyramidal. The common member may be a plate, which may be square, rectangular or circular. The projections may substantially tessellate across the surface of the common member. The projections may have a square or hexagonal base shape. In this alternative, the device may have a mass of at least 10,000 kg, or may be lighter.
Preferably the device comprises a common body to which a working portion may be detachably attached, whereby the working portion may be replaced by an alternative working portion. The device may comprise a plurality of working portions of respective forms.
Preferably, there is at least one working portion which is substantially or generally conical.
There may be at least one working portion which provides a plurality of noses projecting from a common member.
There may be at least one working portion which comprises an elongate and downwardly depending shaft having a relatively narrow nose formed at the bottom thereof.
Preferably the lower end of the shaft carries a head on which the nose is formed. The head may be enlarged in diameter relative to the shaft. The shaft may be approximately 5 m long.
Preferably there is at least one working portion which widens away from the nose when viewed in a first direction, and is substantially constant in width when viewed in a perpendicular horizontal direction.
Preferably a working portion may be attached to and detached from the common member while the common member remains attached to lifting means. The common member is preferably heavier than a working portion.
The invention also provides a ground treatment device, the device being weighted to provide ground treatment by dropping the device on the ground, and the device having a common body attachable to lifting means and to which a working portion may be detachably attached to provide the point of first contact with the ground, the working portion being replaceable by an alternative working portion.
Preferably the common body is heavier than a working portion, to provide the majority of the weight of the device. The working portion may have any of the features or combinations of features set out above.
The invention also provides a method of ground compaction, in which a ground compaction device is dropped to cause ground compaction, the device being so shaped as to embed when dropped, and in which the degree of compaction is monitored by dropping the said device onto compacted ground at a predetermined speed, and noting the depth to which the device becomes embedded.
The predetermined speed is preferably achieved by dropping the device from a predetermined height above the ground.
The device is preferably calibrated by selection of its shape and/or weight to cause the device to embed by less than a predetermined depth when the ground is compacted to or above a predetermined degree. The device is preferably formed to provide a visual indication of having embedded to the said predetermined depth. Preferably the device comprises a projection or marking spaced by the said predetermined depth from the lowermost point.
The device is preferably a ground compaction device according to any of the definitions set out above.
The ground may be prepared prior to compaction by forming columns of particulate material therein, for allowing water movement in the ground. The material of the columns may be stone, rubble or the like.
Preferably the holes formed in the ground by embedding of the compaction device are filled after compaction. The holes may be filled prior to monitoring the compaction attained. The holes are preferably filled by disturbing and levelling the surface of the area being compacted.
The invention also provides a method of forming a support within the ground, wherein a ground treatment device as aforesaid is dropped to create a void in the ground, and the void is filled with supporting material.
Preferably a pillar of particulate material such as stone, is first formed in the ground, the ground treatment device being dropped onto the pillar to form a void at the top thereof.
The supporting member may be concrete.
A pile may be driven into the ground, through the void. The void may be filled before the pile is driven. The pile may be driven by the ground treatment device.
The invention also provides ground compaction apparatus comprising a weight for compaction of the ground by impact, drive means operable to lift the weight prior to dropping, and control means operable to move the apparatus substantially automatically between drops of the weight.
Preferably the apparatus has ground wheels, skids or tracks by which the apparatus may be moved. Preferably the control means are operable to cause the apparatus to move while the weight is being lifted. The control means may cause the apparatus to move by a predetermined amount after each weight drop. The predetermined amount is preferably settable in accordance with the ground condition. The control means may comprise override means by which an operator may control the distance the apparatus moves after each drop, in response to the operator""s assessment of ground condition.
The apparatus preferably moves with the weight at the rear of the apparatus.
Preferably fixed means are provided to define a line across ground to be compacted, the apparatus being operable to follow the defined line when moving. The fixed means may comprise a laser operable to project a beam across the ground to be compacted.
Preferably the apparatus is mounted on roadworthy ground wheels whereby the apparatus may be driven to an alternative site without external power.
Preferably the apparatus comprises guide means operable to guide the weight as it falls. The guide means may comprise slots which are substantially vertical in use, the weight having members which run in the slots as the weight falls. The drive means may be disengageable prior to dropping, whereby the weight may substantially freefall to the ground. The apparatus may further comprise releasable lock means operable to retain the weight in a raised position supported by the guide means, thereby removing load from the drive means prior to dropping the weight.
Preferably the guide means are mounted on sled means moved during use by dragging. The guide means may be movable to a stowed condition when not in use. The guide means may have two hingedly connected parts allowing stowage. Shock absorbing means may be provided for the guide means, to absorb shock imparted to the guide means on impact of the weight with the ground.
The invention also provides ground compaction apparatus comprising a weight for compaction of the ground by direct impact on the ground, drive means operable to lift the weight prior to dropping, and guide means operable to guide the weight as it falls.
The guide means may comprise slots which are substantially vertical in use, the weight having members which run in the slots as the weight falls. The drive means may be disengageable prior to dropping, whereby the weight may substantially freefall to the ground.
The guide means may be movable to a stowed condition when not in use. The guide means may have two hingedly connected parts allowing stowage. Shock absorbing means may be provided for the guide means, to absorb shock imparted to the guide means on impact of the weight with the ground.
The apparatus may further comprise releasable lock means operable to retain the weight in a raised position supported by the guide means, thereby removing load from the drive means prior to dropping the weight.
Preferably the apparatus has ground wheels or tracks by which the apparatus may be moved. The apparatus is preferably powered for movement. Control means may be operable to cause the vehicle to move between successive drops of the weight. Preferably the control means are operable to cause the vehicle to move while the weight is being lifted. The control means may cause the vehicle to move by a predetermined amount after each weight drop. The predetermined amount is preferably settable in accordance with the ground condition. The control means may comprise over ride means by which an operator may control the distance the apparatus moves after each drop, in response to the operator""s assessment of ground condition.
The apparatus preferably moves with the weight at the rear of the apparatus. Preferably the guide means are mounted on sled means moved during use by dragging.
Preferably fixed means are provided to define a line across ground to be compacted, the apparatus being operable to follow the defined line when moving. The fixed means may comprise a laser operable to project a beam across the ground to be compacted.
Preferably th e guide means is movable to a stowed condition when not in use.
Preferably the apparatus is mounted on roadworthy ground wheels whereby the apparatus may be driven to an alternative site without external power.
The invention also provides a method of ground compaction, in which fixed means are provided to define a line across ground to be compacted, and compaction apparatus is arranged to follow the line so defined when moving between drops.
Preferably the fixed means comprises a laser to project a beam across the ground, the compaction apparatus having sensor means operable to detect and follow the beam.
Preferably the compaction apparatus is as defined in any of the definitions set out above.
The invention also provides a method of ground compaction in which initial ground compaction is achieved, and in which an ironing pass is then effected by using a ground treatment device having a plurality of upwardly widening noses is then dropped onto the ground being treated, and in which the ground being treated is subsequently rolled.
Preferably depressions formed by the noses are filled before rolling. Initial compaction may be achieved by means of a ground compaction device as set out above. The ironing pass preferably covers substantially the whole area of the ground.